Like Rihanna’s Good Girl Gone Bad, this album tells its story backwards; and it similarly begins with a redemptive hymn involving water. I am sure that some listeners remain mystified as to why Bridge Over Troubled Water begins rather than ends with its title song, but the record’s architecture – since, as a record, it is so concerned with architecture – has its own, partially eluctable logic.

The key to why this record, of all farewells to the sixties, so dominated the first half of the seventies – its cumulative run of 33 weeks at number one is the longest achieved by any non-film soundtrack album, and it notched up a total of 307 weeks on our charts, enduring almost into the age of punk (with a couple of brief reappearances in the mid-nineties) – is perhaps because its goodbyes are so personal and yet so non-specific. By 1969 Paul Simon had felt that the duo had run its course; at times they were barely on speaking terms – but they had been friends, collaborators even, since childhood, and the farewell was a protracted and deceptively painful one. Look at the front cover; Simon, grinning and seemingly not giving a damn, looking remarkably like the younger de Niro, with a grim ghost standing almost twice his height behind him – and then, on the back cover we see Garfunkel strolling away, hands in pockets, with Simon walking behind him, his head buried in Garfunkel’s upper back.

On the title song itself, Simon is of course the ghost; he wrote the song but does not appear on it at all – the late Larry Knechtel played the piano (and received a full credit on the 45 release) and the harmonies in the final verse are all overdubbed Garfunkels. He did sing the original demo, however, and both Garfunkel and producer Roy Halee were keen for him to perform the song on the record – Art had a thing for Paul’s falsetto – but he demurred. Likewise his original plan had been to keep the song quiet, hushed, but Garfunkel and Halee persuaded him to add the “Sail on silvergirl” coda and the big Righteous Brothers finish.

In the event, Garfunkel sang it alone, as alone as the Gerry Marsden of “You’ll Never Walk Alone,” although the song is about reassurance, the painful reattachment of hope and trust. He sings the first verse as quietly as anyone could bear to sing it, a verse about weariness and smallness, and he tries to reassure the song’s subject – which, as with other songs on the record, can only really be about Paul saying farewell to Art – that they will not encounter hopeless emptiness, that although the street on which the hapless fugitive may find himself may be as direly unforgiving as the Gibsom Street described in the first half of Laura Nyro’s song of the same name – and New York Tendaberry is the mirror image of Bridge in so many ways – there will be a light, there will be…him, for what he’s worth.

A vibraphone steals into the second verse, giving a floating unearthliness comparable with the closing section of George Crumb’s Makrokosmos III, but see how Garfunkel’s voice and emotion both rise markedly at the phrase “And pain is all around”; Knechtel’s piano becomes more emphatic, and therefore hopefully more empathetic. The risk of salvation is signalled by Hal Blaine’s rhetorical cymbal at verse’s end; the waters briefly settle again, only to receive a flotilla of strings, Blaine’s distant drums approaching, two basses, each entering from either channel, a patter that feels like the earth beginning to move. “See how they shine,” the doubled-up Garfunkels state, far more firmly than before, as the solo Garfunkel’s gasp of “Oh!” is met by Joe Osborn and/or Carol Kaye’s octave-surfing bass(es), and suddenly the Spector reclamation makes sense – this is an “Unchained Melody” for a lost cause of a generation, Garfunkel making with the Bobby Hatfield high Cs, busting the ebbing tide as Blaine’s thunderclap hails a new man, finally settling on a ten-second high string coda, in E major – the same chord which ends “A Day In The Life.” The bridge has been crossed as securely as the long Lew Soloff note which ends Nyro’s “Save The Country” and the message is; hang on, everybody, it’s safe to go in, to go ahead, we can’t get hurt now. Both Aretha and Elvis, in their versions, took the song back to church, where it always belonged, but Art and the spectre (Spector?) of Paul are saying: we will have to end, but the world will go on, you will go on, and hence we will go on in our own selves.

From the thunder of their bay we retreat to the quiet disturbances of Peru, as Paul sets about figuring out his own future; featuring the Peruvian group Los Incas and based on a Peruvian folk song which was slightly newer than Simon initially imagined, “El Condor Pasa” sees him wistfully dreaming of another world (“I’d rather be a forest than a street”), another life (“I’d rather be a sparrow than a snail”), interspersed with regretful musings about departing swans. He wants to feel the earth beneath his feet and isn’t sure that New York, or the sixties, or for that matter Art Garfunkel, can provide it for him.

Both “Pasa” and “Cecilia” mark the beginnings of Simon’s wider journeys into the worlds of music, a journey which would reach final fruition some sixteen years later. With its over-frantic handclaps, rattling percussion and askew calliope and bamboo flutes, there is a case for “Cecilia” inventing Vampire Weekend, although the song seems less of a complaint about an unfaithful woman than a desperate call to an absent muse, Cecilia being the patron saint of music. He gets out of bed to wash his face, comes back and there’s someone else there, but unlike the not dissimilar progenitor of Leonard Cohen’s “Dress Rehearsal Rag,” he finds his muse again, afresh. “JubilAAAAtion!” he cries. “She loves me again! I fall on the floor and I laughing!” he proclaims in a slightly cod JA accent (there certainly is a feel of nascent reggae about the song).

As we proceed to “Keep The Customer Satisfied,” the album’s developing theme appears to be that of Paul Simon’s lost muse and his struggle to stay afloat, either with or without it; Paul and Art’s opening gust of “Gee but it’s great to be back home!” is a brighter-painted variant on the getting back home theme which has been prevalent over the last dozen or so entries in this tale; they’re out there on the road, getting shit, getting moved on, but as tired as they are, they have to keep on going, continue to pump the oxygen that powers the excitable-verging-on-hysterical big band behind them (although the latter are secretly powered by Knechtel’s liquid organ). Finally, Blaine’s snare drum becomes more insistent; their final “So tired” seems wrenched from the backs of their throats, and Lew Soloff is back again with his unresolved high C climaxes.

On first listen, “So Long, Frank Lloyd Wright” is the hardest song to place in terms of this record’s story, and musically it is by some distance the strangest; it owes its disturbed glide to Lennon’s “Julia,” its general, edgily easy ambience and unorthodox chord progressions to Antonio Carlos Jobim. And Art is singing lead. Why a paean to the great American architect, some ten years after he had left? Is this a requiem for an America which, by 1970, had passed into irretrievable history? But then we hear “All of the nights we’d harmonize ‘til dawn” and “When I run dry/I stop awhile and think of you” and we realise that this nocturnal meditation is, again, Paul saying farewell to Art – and, again, he gets Art to sing the song. As Jimmie Haskell’s arrangement dissolves into a dissolute flute solo, strings chirping like insomniac crickets, Garfunkel turns the final “I never laughed into long” into a loop of “So long”s until Simon, in the distance, grunts “So long already, Artie!”

"The Boxer" finds Paul enlarging and expanding the feeling of impatient abandonment he had first articulated in “Homeward Bound” (“In the quiet of the railway station/Running scared/laying low” – did you catch another Orbison reference there?). As with the title track, "The Boxer" patiently builds up its sonic palette as it progresses through several states of emotional being.

Beginning with simple acoustic guitar and hand percussion, "The Boxer" is a song about defeat; its progenitor is more “settled” than that of “America” but he is now also unavoidably alone. He has moved to New York, has found its demands too much for him to take, and wonders about abjectly sloping back home ("Still the man hears what he wants to hear and disregards the rest" is, I am aware, a leitmotif which could be used against virtually every writer, if not every human being). There’s a touch of Harold Biffen about Simon’s Biblical eagerness to be "Seeking out the poorer quarters where the ragged people go/Looking for the places only they would know":

"He could not bear to walk the streets where the faces of beautiful women would encounter him. When he must needs leave the house, he went about in the poor, narrow ways, where only spectacles of coarseness, and want, and toil would be presented to him. Yet even here he was too often reminded that the poverty-stricken of the class to which poverty is natural were not condemned to endure in solitude. Only he who belonged to no class, who was rejected alike by his fellows in privation and by his equals in intellect, must die without having known the touch of a loving woman’s hand"

(George Gissing, New Grub Street, chapter 35, "Fever And Rest")

Note that Simon could sneak the word "whores" (1:27) onto mainstream radio without anyone really noticing; note further his contented "mmm"s after confessing that he has sought the solace of such pleasures (1:38).

Gradually and subtly the song’s architecture builds itself up, Fred Carter Jr’s busy acoustic guitar rendering it a quieter reverse image of “Mrs Robinson” (Simon phrases “so lonesome” to make it sound like “solo”; the rhetorical rest where “bleeding me” seems almost indistinguishable in tone and intent from “leaving me”); there’s a momentary, mournful pedal steel interlude and also a bass harmonica hovering in the background which suddenly moves to the fore when Simon uses the "boxer" analogy – the fulcrum of the track is the moment at 3:03 when everything – voice, harmonica, music – suddenly jab out savagely with the word "cut" in the line "Every glove that laid him down and CUT him ‘til he cried out…"The song builds to an alienated climax, firstly with the same echoed whiplash drums we find on "”Bridge," the increasing intensity of the "lie-la-lie" refrain (is he simply telling lies here, or lying down to lick his wounds, or worse?) – followed at 3:59 by the entrance of a mellotron, and – devastatingly – at 4:19, the ominous Moog bass (Lena calls it “The biggest foghorn in the world!”) which suddenly bursts into the song and threatens to crush it altogether (the first appearance of a synthesiser on a UK Top 40 single). Everything peaks at 4:30 when real strings come in, violins shrieking – or weeping? – in entwinement with the Mellotron strings. And finally, as Simon’s progenitor returns home – or so he imagines - the song returns to its original state – with a codicil from Garfunkel, indistinct and buried in the mix, at 4:45-4:46; but it’s there – "I love you," almost whimpered through his transient tears. There may be some residual “Hey Jude” influence, but then again, isn’t the love Paul needs, as the album cover demonstrates, on his shoulder?

“Baby Driver” follows with an air of much-needed light relief (or so it would superficially seem); its racy swing, as with several other tracks on the record, would not have been out of place on the White Album. Starting off with crisp tambourine and acoustic guitar, the duo indulge in comedy hi-falsetto harmonies (“GONE uhhh!”) as Simon considers whether the girl next door will accept him as a new Everyman; parents as musicians, soldiers, businesspeople, but only the music stays with him (“coming in my ears”). A throaty, raspy R&B tenor (backed up by an equally throaty baritone) hurls itself into the song’s speeding melee midway through, and the song itself moves up a key before vanishing in the forest of engine roars – its key moment coming in the second verse where Simon admits, almost as a throwaway, “When I was young, I carried a gun/But I never got the chance to serve…I DID NOT SERVE.” Isn’t there a war going on somewhere?

“The Only Living Boy In New York” is a more emotionally open and considerably more poignant variant on the “Frank Lloyd Wright” farewell; here Paul finally yields to emotion and takes on the vocal. “Tom” is Art, on his way down to Mexico to film his part in Catch-22. Paul considers the song’s implications slightly lazily – his idle “da-n-da-da-n-da-n-da-da and here I am”s – but, as with “Bridge,” the third and final verse ups the passion ante, with its direct references to the earlier song (“eager to fly now,” “shine”). Paul sings the climactic chorus with a tremble and is barely holding himself together; this, after all, is a final farewell from Jerry to a spent joint life. Stentorian drums and organ give the unexpected illusion of Procol Harum before the chorus returns one final time, in turn leading to an elongated coda, led by Osborn’s bass. The multiple “here I am”s dissolve into each other and couldn’t be further away from the Al Green concept of “Here I Am”; there is now no way back as he imagines the ‘plane, his buddy, disappearing – not even any talk of funny papers or negotiations; the finality is unturnable.

The record concludes – or begins - with three relatively quick codas. “Why Don’t You Write Me?” sees Simon stranded in the jungle (Vietnam again, or a jungle of his own making?) but the music is comically, jerkily happy; he turns his “to be near you” into a gargling yodel (“youUUUUUU-LALALAAAA”) but the unexpectedly sombre “something is wrong” which immediately follows illustrates a mind near the end of somebody’s tether; both Newman and Nilsson took this approach to greater extremes in their work of the period, but Simon wriggles on the abyss of existence like any besotted 1960 Highschool moper waiting for school to restart; where’s that letter? He’ll sit in the sun, drink iodine, hang himself, and maybe this rag is as much a dress rehearsal as anything Brian Hyland might once have crooned but he can’t understand how it’s all ended up like this, even though he scripted the end.

And then, back to the source of the pain, the throwback to when they were Tom and Jerry and all they wanted to be were the Everlys; their “Bye Bye Love” is the record’s spookiest track, bookended by extended rounds of applause but the “live” format sounds artificial, grafted on, and eventually we realise that we are listening to the mass movement of synthesised handclaps as the two jauntily announce that they’re through with everything. Don and Phil had that spice, that latent attack, in even their mopiest mopings – as in, you think this is gonna get us down, bud, well you’re WRONG – but Paul and Art are businesslike; this is it, this is how we started and this is how we’ll finish. Now let’s try pulling away from each other. Not that easy, is it?

Lastly – after the taped applause which feeds into plaintive acoustic guitar, just like Pepper – Simon offers his nascent testament, 99 seconds of “Song For The Asking,” clearly addressed to the listener, although the arrangement is made less clear by swamps of electronic echo, strings (in the “thinking it over” section) and even a “Good Night” choir which may be real or synthesised. Still, he is alone, with us, and looking at us, telling us what he still has to offer, what he always had to offer from the beginning, and – well, if you want it, here it is, “all the love that I hold inside.” Can you forgive him, he doesn’t ask (but deeply implies), as a concluding upward Nashville whimper closes the record. Thirty-seven-and-a-half minutes, then, of rhymes of goodbye – to old friends, to the sixties – but still offering a branch of welcome to escort the weary, wasted travellers into another age; the bridge meant something specific to its writer and performer, but could mean anything and everything to those wishing to identify, or indeed follow. There were the sixties, here is the canyon, and we're building a bridge so you can look back at the past but not fall into a worse fate while searching for the future.